Simulating oil droplet underwater dispersal from a condensate field spill in the South China Sea

Abstract

A better understanding of oil droplet dispersal, oil-water interaction, and transport in the South China Sea (SCS) is needed to enhance the response to potential spill risks from subsea oil and gas development in the region. Herein, an offline oil spill prediction system was employed considering the physical processes of hydrocarbon from the leakage source to the sea surface. The components of this system included the droplet size distribution, plume dynamics, hydrodynamics, and Lagrangian particle. The system was applied to simulate a hypothetical spill occurring in a deepwater condensate field. The results predicted a stratification-dominated plume captured by neutral buoyancy at 282 m above the source. Submerged oil droplets were transported in the 60° and 240° directions and the diffusion range gradually expanded. The first oil droplet reached the surface 22 h after the release began. More than 99% of the oil droplets floated up into the upper water column after 50 h. Particularly, droplets larger than 4 mm mainly contributed to the oil slick. After 72 h, the distribution area of the oil slick on the sea surface was ∼18 km2. The simulation results would be valuable for contingency planning regarding the emergency response to an underwater oil spill.